1. Field of the Invention
The present invention relates to an auto-detection circuit and control method for video signals, and more particularly, to an auto-detection circuit and control method for auto-detecting video signals by utilizing a negative voltage characteristic of synchronization signals.
2. Description of the Prior Art
With the advancement of multimedia technology, there are more and more varieties of image and video output devices, such as DVD players, video game consoles, and TV boxes. Therefore, in order to display video signals outputted by the video output devices, many video signal input terminals are built into prior art display devices for receiving and displaying the video signals.
Please refer to FIG. 1. FIG. 1 is a schematic diagram of a prior art display device 10. The display device 10 is capable of receiving and displaying the video signals of the various video output devices. When users want to watch the video outputted by one of the various video output devices, the users can switch the video sources in sequence to obtain the video signal of the desired video output device by pressing a button 110 on the display device 10 or a button 120 on the remote control. In other words, when switching the video sources, the users have to press the button 110 of the display device 10 or the button 120 of the remote control to manually switch to the wanted video source. Thus, the operation of the prior art display device 10 is very inconvenient for the users.
Furthermore, when more video signal input terminals are set on the display device 10, the users have to spend much more time to switch to the correct video source. In this case, both the inconvenience and operation difficulty for the users are increased.